Credit for military service for members of fund B.

(b) Notwithstanding the provisions of subsection (a) of this section, the municipal employer of any member who applies on or after July 1, 1986, for such military service credit shall pay all contributions required under said subsection which are attributable to that portion of the member's military service time during which he was a prisoner of war, provided such member submits with his application for such credit sufficient proof from the United States Department of Veterans Affairs that he is a former prisoner of war. Any municipal employer which pays the contributions required under this subsection for a member who later receives a retirement allowance for permanent and total disability under this part shall, upon its written request, be refunded all such contributions paid under this subsection, provided such military service credit did not serve to increase the amount of disability retirement benefits for which the member was eligible.